What Is PNL in Trading: Gamma Squeeze Impact

This content is for informational and educational purposes only. It does not constitute financial advice, investment advice, or a recommendation to buy or sell any securities or financial instruments. Trading options involves significant risk of loss. Past market events (including those referenced in this article) are not indicative of future results. Always consult a qualified financial professional before making investment decisions.

If you have seen a stock price surge 50% or more in a single session and wondered what was driving it, a gamma squeeze may be the explanation.

A gamma squeeze is a rapid stock price surge in the stock market that occurs when market makers, the firms on the other side of options trades, are forced to buy large quantities of shares to hedge their exposure as call options move closer to being in-the-money. The more the stock rises, the more shares market makers must buy to stay hedged, creating a self-reinforcing feedback loop that can drive prices sharply higher in a short period.

The meaning of a gamma squeeze comes down to one core mechanic: options buying forces share buying, which drives prices up, which forces more share buying. Understanding what it means for your trading account matters because the event directly affects the value of any options positions you hold. This guide covers the mechanics step by step, compares a gamma squeeze to a short squeeze, walks through real examples, and shows exactly what one does to your PNL (Profit and Loss) with concrete numbers.

Options Basics You Need to Know First

Call options, the options Greek called delta, and a practice called delta hedging form the foundation of every gamma squeeze. Here is what each one means.

What Are Options and Call Options?

A call option gives the buyer the right, but not the obligation, to purchase 100 shares of a stock at a specific price (the strike price, also called the exercise price) before a set expiration date. The options premium is the price you pay to buy an options contract, and it represents your maximum potential loss on a long options position. Unlike a put option (which gives the right to sell shares and profits when a stock falls), a call option profits when the stock rises.

One options contract controls 100 shares of the underlying stock. When market makers sell 1,000 call contracts, they may need to buy up to 100,000 shares to hedge their exposure. That amplification is what makes retail options buying capable of moving stock prices.

What Are the Options Greeks?

Options traders use a set of measures called the Greeks to understand how an option's price will behave. Each Greek measures a different dimension of risk: delta measures price sensitivity, gamma measures the rate of change of delta, theta measures time decay, and vega measures sensitivity to volatility. You do not need to master all four to understand a gamma squeeze. For this topic, delta and gamma are the two that matter.

What Is Delta in Options Trading?

Delta (an options Greek) measures how much an option's price is expected to change for every $1 move in the underlying stock. A call option with a delta of 0.50 gains approximately $0.50 in value for every $1 the stock rises. Delta for call options ranges from 0 to 1, and for put options from -1 to 0. When a market maker sells call options, they acquire delta exposure that changes as the stock price moves. That changing delta is where gamma enters the picture.

What Is Gamma in Options Trading?

Gamma (an options Greek) measures how quickly an option's delta changes when the stock price moves $1. Think of it this way: if delta is your car's current speed, gamma is how fast you are pressing down on the accelerator. A small press means your speed changes slowly; a hard press means your speed changes fast.

If a call option has a delta of 0.40 and a gamma of 0.05, a $1 rise in the stock price moves that option's delta from 0.40 to 0.45. The option is now more sensitive to further stock price movement than it was before. Gamma is highest for at-the-money options (when the stock price equals or is very close to the option's strike price) that are near expiration. That specific condition is the environment where a gamma squeeze becomes possible.

What Is a Market Maker?

A market maker is a financial institution or firm that continuously buys and sells options contracts, providing liquidity to the market. When you buy a call option on your brokerage platform, a market maker is typically on the other side of that trade. Because market makers sell options and take on directional risk, they must manage that risk mechanically. Their risk management practice is called delta hedging.

What Is Delta Hedging?

Delta hedging is the practice market makers use to neutralize the directional risk of an options position by trading shares of the underlying stock. When a market maker sells you a call option, they take on negative delta exposure: if the stock rises, they lose money on the option they sold. To offset that risk, they buy shares proportional to the option's delta. As the stock price rises and the option's delta increases (because of gamma), they must buy more shares to stay hedged. This continuous adjustment is the mechanical engine that powers a gamma squeeze.

How a Gamma Squeeze Works: Step-by-Step

A gamma squeeze runs on a feedback loop: options buying forces market makers to buy shares, that share buying pushes the stock price higher, and a higher price forces market makers to buy even more shares.

Here is how that loop unfolds, step by step:

1. Retail traders buy a large volume of call options on a stock they expect to rise.
2. Market makers sell those call options, taking on negative delta exposure.
3. To stay hedged, market makers immediately buy shares of the stock proportional to each option's delta.
4. This share buying pushes the stock price higher.
5. As the stock price rises, the options' delta increases because of gamma, requiring market makers to buy more shares.
6. That additional buying drives the price higher still, pushing delta up again.
7. The cycle repeats, with each round of buying accelerating the next, creating a self-reinforcing price surge.

This is the gamma squeeze feedback loop: options buying forces share buying, which drives up prices, which forces more share buying.

What Causes a Gamma Squeeze?

Four root conditions must align for a gamma squeeze to develop:

• Concentrated retail call option buying: A large volume of call options purchased over a short period overwhelms normal market maker hedging capacity.
• Low-float stock with limited shares available: A stock's float is the number of shares available for public trading. When that supply is small, each round of market maker share buying has an outsized effect on the price.
• Options near expiration with high gamma: Short-dated options carry the highest gamma values, meaning each dollar of stock movement forces more aggressive hedging adjustments.
• Stock price near or at a major strike price: Gamma peaks for at-the-money options, so a stock hovering near a heavily populated strike price sits at the point of maximum hedging demand.

Gamma Squeeze vs. Short Squeeze: What's the Difference?

A gamma squeeze and a short squeeze both send stock prices surging, but the forces driving them are completely different.

Unlike a short squeeze, which involves short sellers being forced to cover their borrowed share positions as prices rise, a gamma squeeze is driven entirely by market maker delta hedging of options positions. The two events can occur simultaneously, as happened during the GameStop event in January 2021, where compounding forced buying from both mechanisms produced an extraordinary price surge. When they occur together, the combined upward pressure exceeds either event alone, but the magnitude in any specific case depends on the stock's float, options activity, and short interest.

Real-World Gamma Squeeze Examples: GameStop and AMC

The clearest example of a gamma squeeze in action unfolded in January 2021, when GameStop (GME) became the most closely watched stock in the world.

GameStop (GME): The Defining Gamma Squeeze of 2021

GameStop and AMC Entertainment became known as meme stocks, shares that went viral on social media platforms like Reddit's r/wallstreetbets, driving coordinated retail buying of both shares and call options. In early January 2021, traders on r/wallstreetbets began purchasing large volumes of short-dated call options on GameStop, which carried both substantial short interest and a small float. Market makers who sold those options were forced to buy GME shares to hedge their delta exposure, pushing the price upward. As the price rose, delta increased, forcing even more share purchases in the feedback loop. Hedge funds with large short positions in GameStop found themselves on the wrong side of both a gamma squeeze and a short squeeze simultaneously, adding further forced buying. GameStop's stock surged from approximately $20 in early January 2021 to a peak near $483 on January 28, 2021, before collapsing rapidly in the sessions that followed.

AMC Entertainment (AMC): The Pattern Repeats

A similar dynamic played out with AMC Entertainment (AMC) in May and June 2021, when coordinated retail buying of call options triggered a rapid price surge driven by the same gamma mechanics. The AMC episode confirmed that the GameStop pattern was not a one-time anomaly but a repeatable sequence tied to specific market conditions.

How a Gamma Squeeze Affects Your PNL

A gamma squeeze can shift the value of options positions in your trading account within hours. Here is what that means in concrete dollar terms.

What Is PNL in Trading?

PNL stands for Profit and Loss. In trading, your PNL (also written P&L) is the total gain or loss on a position, telling you in plain terms whether you are making or losing money and by how much. In finance broadly, PNL appears in two contexts: a company's Profit and Loss Statement (also called an income statement), which reports revenues and expenses, and a trader's position-level PNL, which measures the gain or loss on individual trades. This article focuses on the latter.

Unrealized PNL vs. Realized PNL: What's the Difference?

Unrealized PNL is the gain or loss on a position you still hold. It exists on paper but has not been locked in. Traders sometimes call this "paper gains" or "paper losses." Realized PNL is the gain or loss you lock in when you close your position. Once you close a trade, that gain or loss is permanent regardless of what the price does afterward.

Here is how that distinction plays out during a gamma squeeze. Say you bought a call option for $1.50 per contract. During a gamma squeeze, that option's premium rises to $8.00. Your unrealized PNL at that moment is $650 per contract, calculated as ($8.00 - $1.50) x 100. That gain is real on your screen, but it is not yours yet.

If you sell at $8.00, your realized PNL is $650 per contract. If you wait and the price falls back to $2.00 before you sell, your realized PNL drops to only $50 per contract. The squeeze does not care about your paper gains. Only what you lock in counts.

To understand why your closed P&L can sometimes show a loss even when unrealized profit was positive, see Why Closed PL Loss When Unrealized Profit Positive.

How to Calculate Your PNL on an Options Trade

The formula for PNL on a long options position is:

PNL = (Exit Price - Entry Price) x Number of Contracts x 100

Here is the worked example using fictional but realistic numbers:

• Entry Price: $1.50 premium per contract
• Exit Price: $8.00 premium per contract (during gamma squeeze)
• Number of Contracts: 10

PNL = ($8.00 - $1.50) x 10 x 100 = $6,500 gross profit

This $6,500 figure represents realized PNL only if you close the position at $8.00. Subtract brokerage commissions for your net figure. If you hold through a reversal and the premium falls to $2.00, the same formula produces ($2.00 - $1.50) x 10 x 100 = $500.

The Role of Implied Volatility in Your PNL During a Squeeze

Implied volatility (IV) is the market's expectation of how much a stock price will move over a given period. When IV rises, options become more expensive. During a gamma squeeze, IV typically spikes as rapid price movement increases market uncertainty, inflating options premiums beyond the intrinsic value from stock movement alone. (Vega measures how much an option's price changes for each 1% move in implied volatility. During a gamma squeeze, rising IV amplifies vega-driven gains for call holders on top of the gamma-driven price increase.)

The critical risk that follows is IV crush. After a squeeze peaks and the stock price stabilizes or reverses, implied volatility collapses back toward normal levels. This collapse causes options premiums to fall sharply, even if the stock price itself remains elevated. IV crush is the most common reason retail traders watch their unrealized PNL peak and then evaporate before they can close their position.

How to Identify a Potential Gamma Squeeze: 5 Warning Signs

Certain conditions make a gamma squeeze more likely to develop, and traders who recognize them early have more time to assess their positions.

To identify a potential gamma squeeze, watch for these five signals:

• Unusually High Call Open Interest Relative to Float: Open interest (the total number of outstanding options contracts not yet closed or exercised, distinct from daily trading volume) that is disproportionately large relative to the stock's float signals that moderate price movement could force enormous hedging demand on market makers.

• Short-Dated Options Dominating Volume: Weekly or near-expiration options carry the highest gamma, so market makers must hedge more aggressively per dollar of stock movement. A spike in short-dated call volume is a key precursor signal.

• Stock Price Near or Approaching a Major Strike Price Cluster: Gamma peaks for at-the-money options. When a stock price hovers near a level where large numbers of call options have been written, the hedging demand is greatest and the squeeze trigger is closest.

• Implied Volatility Rising Alongside Price Acceleration: Rapidly rising IV concurrent with accelerating stock price movement suggests the options market is pricing in continued large moves, often a signal that institutional hedging activity is building.

• Heavy Retail Social Media Attention and Coordinated Call Buying: When a stock trends on platforms like Reddit's r/wallstreetbets, coordinated retail call option purchases can rapidly build the open interest that creates gamma squeeze conditions.

Both GameStop and AMC exhibited all five of these signals simultaneously in 2021. Recognizing these conditions does not guarantee a squeeze will occur. Multiple factors must align, and identifying these signals does not constitute investment advice.

Can You Profit from a Gamma Squeeze? Risks and Opportunities

Retail investors can profit from a gamma squeeze, but doing so consistently and safely is more difficult than the rapid price movements may suggest.

The Opportunity Side

Call options held before or early in a gamma squeeze appreciate as the stock price rises and IV inflates simultaneously. A trader who held short-dated call options on GameStop before the January 2021 surge saw those contracts multiply in value within days. Shareholders in the affected stock also benefit directly from the price increase. The gains can be substantial for those positioned before the squeeze begins.

The Risks to Understand

Risk Warning: The following risks are real, well-documented, and have caught experienced traders off guard.

• Rapid reversal: A gamma squeeze can reverse within the same trading session it peaks. There is no reliable signal for the exact top.
• IV crush: When the squeeze ends, implied volatility collapses and options premiums fall sharply, even if the stock price holds. A trader who does not close their position before IV normalizes may find that the option worth $8.00 at peak is worth $2.00 the next morning.
• Liquidity risk: In low-float stocks, large sell orders may not fill at expected prices. Slippage can reduce realized PNL significantly from what the screen showed at peak.
• FOMO-driven poor timing: Entering a squeeze after the majority of the move has already occurred means paying peak prices for contracts that are already depreciating.
• Theta decay (the daily erosion of an option's value as expiration approaches) works against call holders if the expected squeeze does not materialize quickly enough.

Whether a gamma squeeze is positive or negative for your trades depends entirely on your position. Call holders and shareholders gain as the price rises. Short sellers and traders who sold call options face losses. Even call holders can lose money if they hold through the reversal rather than locking in their realized PNL near the peak.

For context on how market makers differ from speculative traders in their obligations and behavior, see Differences Between Speculators And Market Makers.

Frequently Asked Questions About Gamma Squeezes

These questions come up most often among traders who first encounter the term gamma squeeze.

What is a gamma squeeze in simple terms?

A gamma squeeze is a rapid stock price surge caused by market makers buying shares to hedge their risk after a flood of call options are sold to retail traders. The more the stock rises, the more shares market makers must buy, creating a self-reinforcing cycle of upward price pressure.

How long does a gamma squeeze last?

A gamma squeeze typically lasts anywhere from a few hours to a few days. Unlike a short squeeze, which can persist for weeks as short sellers slowly cover their positions, a gamma squeeze is often more abrupt and can escalate and reverse within a single trading session, particularly for options expiring in the near term. The reversal tends to be rapid, which is why timing the exit matters for locking in realized PNL.

What is the difference between a gamma squeeze and a short squeeze?

A gamma squeeze is driven by market makers forced to buy shares to hedge their delta exposure from call options they sold. A short squeeze is driven by short sellers forced to buy shares to cover losing short positions. Same surface result (rapidly rising price), completely different cause. See the full comparison table above for a side-by-side breakdown.

Can retail investors profit from a gamma squeeze?

Yes, but the difficulty should not be underestimated. Call options held before the squeeze can appreciate substantially in value. However, timing the exit is genuinely difficult, IV crush can eliminate much of the gain after the peak, and reversals happen fast. Traders who chase the move after it is already underway often pay peak prices for rapidly depreciating contracts.

What stocks are most prone to gamma squeezes?

Gamma squeezes are most likely in stocks that combine a small float, unusually high call open interest relative to that float, short-dated options dominating volume, and a stock price near a major strike price cluster. Heavy retail social media attention can accelerate the buildup of these conditions. These are characteristics to screen for, not a guarantee.

What is PNL in trading?

PNL stands for Profit and Loss. In trading, it is the total gain or loss on a position. In options trading during a gamma squeeze, your PNL reflects how much your call options have gained or lost in value relative to what you paid for them.

What happened during the GameStop gamma squeeze?

In early January 2021, traders on Reddit's r/wallstreetbets coordinated large-scale purchases of call options on GameStop (GME), a stock that also carried substantial short interest. Market makers who sold those options were forced to buy GME shares to hedge their delta exposure. A simultaneous short squeeze compounded the pressure from short sellers covering their positions. GameStop surged from approximately $20 to a peak near $483 on January 28, 2021, before reversing sharply in the following sessions.

Is a gamma squeeze good or bad for my trades?

It depends entirely on your position. A gamma squeeze benefits traders who hold call options or shares in the affected stock, as the rising price increases position value. It harms short sellers and traders who sold call options. Even call holders can lose money by holding through the reversal rather than selling near the peak.

Key Takeaways: What You Now Know About Gamma Squeezes and PNL

The core ideas from this article, distilled:

• A gamma squeeze is a rapid stock price surge driven by market makers forced to buy shares to hedge their delta exposure from call options they sold.
• The feedback loop is self-reinforcing: buying drives the price up, which increases delta (because of gamma), which requires market makers to buy more shares.
• Options mechanics drive a gamma squeeze; short sellers covering their positions drive a short squeeze. Both can occur simultaneously, as in GameStop January 2021.
• During a gamma squeeze, your unrealized PNL can spike rapidly, but only your realized PNL, what you lock in by closing the position, is money you actually keep.
• IV crush after the squeeze peak can rapidly destroy unrealized options gains even if the stock price holds, because implied volatility collapses and premiums fall.
• Warning signs include unusually high call open interest relative to float, short-dated options dominating volume, and stock price near a major strike price cluster.
• Trading a gamma squeeze carries significant risks including rapid reversal, IV crush, and liquidity issues in low-float stocks.

To build on this foundation, explore how take-profit and stop-loss orders work in practice for a practical look at the tools traders use to lock in realized PNL before a reversal erases their gains.

Related reading:

• Why Closed PL Loss When Unrealized Profit Positive
• Differences Between Speculators And Market Makers
• Introduction To Take Profit And Stop Loss Spot Trading